1. Field of the Invention
The present invention relates generally to a power amplification apparatus, and in particular, to a power amplification apparatus in a mobile communication system.
2. Description of the Related Art
In general, a mobile communication system such as a code division multiple access (CDMA) communication system, has a power amplifier (PA) included in its output stage. Power amplifiers power-amplify a radio frequency (RF) signal to provide a signal having an appropriate level for transmission over a radio path via an antenna.
FIG. 1 is a diagram illustrating an example of a prior art power amplification apparatus in a 3-sector antenna system. FIG. 1 is a power amplification apparatus in a 3-sector antenna system having α, β and γ sectors. The power amplification apparatus includes power amplifiers (PAs) 100 which are independently driven in association with corresponding sectors. When many calls are concentrated in a certain sector, the power amplifier for the sector has a heavy load. In order to sufficiently provide services desired by a user to the sector having a heavy load, capacity of the corresponding power amplifier must be increased. Since such a situation may occur for all sectors in the same way, there is a necessity to set capacity of every sector's power amplifier to its maximum possible value.
However, since call distribution per sector is not uniform according to time and sector, a method of setting capacity of every sector's power amplifier to its maximum value may be inefficient in terms of utilization of the power amplifiers. In particular, the life span of a power amplifier having a heavy load is decreased compared with power amplifiers not under a heavy load.
Meanwhile, the conventional power amplification apparatus can include a redundant power amplifier to handle situations in which a service is dropped due to a failure of a certain power amplifier. However, the redundant power amplifier does not operate while the other power amplifiers are being driven, thus increasing inefficiency in terms of the overall utilization of the power amplifiers.